decoding 2d bar code,why the performance is not well

now,i am developing a 2d barcode system,
and the performance is not very well,i think it can be improved,because some one in my company
have done this,but he is not in the company now.i have the decode alogrithm,but not the framework
can any one suggest a good framework.my code is below.

my devices is N73.
first start view finder with size(240,180)
void CCameraCaptureEngine::ViewFinderFrameReady(CFbsBitmap& aFrame)
{
TUint8* dataAddr=(TUint8*)(aFrame.DataAddress());
iCodeSearch->InputData(dataAddr,240,180,32);
TInt result=iCodeSearch->Recognise();
if(result==1)
{
AsyncStateChange(ERecognizeSucc);
}
}

i found it is not very well,